1. Field of the Invention
The present invention relates generally to a device for writing optical information and more particularly to a device for writing optical information, employing a self-scanned recording element.
2. Discussion of Background
Self-scanned recording elements serve to convert image signals to corresponding spatially arranged light signals. Examples of such self-scanned recording elements include an LED array, a liquid-crystal shutter array, a fluorescent dot array, and the like. The fluorescent dot array comprises an array of fluorescent layer dots disposed on an electrode array, with the fluorescent layer dot array and a wire electrode sealed in a vacuum chamber. Thermions or thermoelectrons emitted from the wire electrode are attracted by the electrode array to hit the fluorescent layer dots, causing the latter to emit fluorescent light.
One recently proposed optical information writing device employing such a self-scanned recording element is illustrated in FIG. 5 of the accompanying drawings. As shown in FIG. 5, an image-forming optical system 40 is interposed between an LED array 30 serving as a self-scanned recording element and a photosensitive recording medium 50 such as a photoconductive photosensitive body on which optical information is to be written. The direction normal to the sheet of FIG. 5 will hereinafter be referred to as a Z direction.
The image-forming optical system 40 comprises a roof mirror array 42, a lens array 44, a right-angled mirror 46, and a housing 48 accommodating the roof mirror array 42, the lens array 44, and the right-angled mirror 46 in mutually spaced relationship. The roof mirror array 42 is of a structually integral optical component having an array of roof mirrors arranged at a constant pitch in the Z direction, each of the roof mirrors having a ridge extending vertically in FIG. 5. The lens array 44 includes an array of lenses arranged in the Z direction at the same pitch as that of the roof mirrors of the roof mirror array 42. Each of the lenses of the lens array 44 is optically associated with one of the roof mirrors of the roof mirror array 42.
Each of the lenses of the lens array 44 and the corresponding roof mirror combined therewith jointly constitute a retrodirective image-forming optical system for forming an unmagnified image of an object on a surface of the object. Therefore, the roof mirror array 42 and the lens array 44 jointly constitute an array of such retrodirective image-forming optical systems.
The right-angled mirror 46 comprises two plane mirrors which are elongate in the Z direction, the plane mirrors having mirror surfaces normal to each other. The roof-mirror array 42, the lens array 44, and the right-angled mirror 46 are retained in the housing 48 as shown in FIG. 5. The housing 48 has a pair of slits extending in the Z direction and aligned vertically with each other, with cover glass strips 41, 43 fitted in the respective slits.
The surface of the LED array 30 from which light signals are emitted and the photosensitive recording medium surface are held in unmagnified-image-forming relationship by the image-forming optical system 40. When the LED array 30 is energized, light emitted therefrom enters the image-forming optical system 40 through the cover glass strip 41 in the upper slit of the housing 48 and is reflected to the right by the right-angled mirror 46. Then, the light passes through the lens array 44 and is reflected by the roof mirror array 42 back through the lens array 44 to the right-angled mirror 46. The light is reflected by the right-angled mirror 46 to exit from the image-forming optical system 40 through the cover glass strip 43. The light then falls on the recording medium 50 to form an image produced by the light emitted from the LED array 30.
By moving the surface of the recording medium 50 in the direction of the arrow while applying an image signal to the LED array 30 to enable it to generate optical information representative of the image signal, such optical information can be written or recorded on the recording medium 50. Where the recording medium 50 is a photoconductive photosensitive body, an electrostatic latent image corresponding to the image information can be formed thereon by such an information writing process.
With the optical information writing device shown in FIG. 5, however, the surface of the self-scanned recording element from which light signals are produced and the recording medium surface must be held in proper unmagnified-image-forming relationship through the intermediary of the image-forming optical system. It has been tedious and time-consuming to adjust the relative positions of the self-scanned recording element, the image-forming optical system, and the recording medium.
There have been developed mass-producible self-scanned recording elements of low power requirements, which are of a compact construction having a light signal generator and a driver circuit that are formed integrally on one substrate in in-line configuration.